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At least 577 records · Page 32Linked to original sources
PubMed1999

Moderate renal failure in association with prolonged acquired hypothyroidism in children.

We evaluated five children with prolonged primary hypothyroidism and noted a significant reduction in renal function (40%), which was reversible with hormonal replacement. This decline was higher than reported in adults and was of sufficient magnitude to warrant altering drug-dosing schedules. Furthermore, patients with moderately reduced renal function should be carefully evaluated for signs and symptoms of hypothyroidism.

Adolescent↗
PubMed1977

Iodinated radiological contrast media as radiosensitizers.

This paper describes the radiosensitizing effects of diatrizoic (DA) and iothalamic (ITA) acids and of iodipamide (IP) on the survival of E coli B/r irradiated with X-rays and with high-intensity electron pulses. All compounds at concentrations between 10 and 50 mM display a strong sensitizing effect in the presence of oxygen (DMF between 0-1 and 0-3) and are much less effective in nitrogen. In N2O the degree of sensitization is intermediate between oxygen and nitrogen. The situation is the same at pH 7 or 5-6. Solutions of DA, ITA and IP irradiated at pH lower than 6 become highly toxic to bacteria added after irradiation, for several hours after X-irradiation or several minutes after pulsed irradiation. The maximum toxic effect occurs with 2 krad of X-ray and with 6-8 krad of electrons. Oxygen must be present in order to observe the bactericidal activity. This is not affected by scavenging hydrated electrons with nitrate, but is completely cancelled by scavenging OH radicals with formate. It is also cancelled by adding thiosulphate to the irradiated solutions immediately before the bacteria. In the presence of nutrient broth, the radiosensitizing effect is absent after irradiation with pulsed electrons; whereas after X-irradiation it is reduced when the concentration of sensitizers is 50 mM. The experimental data appear to be compatible with a mechanism operated by short and long-lived transients resulting from the radiolysis of iodinated contrast media.

Cell Survival↗
PubMed1986

Radiation chemical and physical mechanisms of radiosensitization of single cell systems by iothalamate.

The radiosensitizing effect of iothalamate (ITA) has been investigated in bacterial and mammalian cells in order to obtain a better understanding of the physical and radiation chemical mechanisms of sensitization displayed by the drug. In order to distinguish between the two, Escherichia coli B/r cells were irradiated with 9 MeV electrons, which allow only the radiation chemical mechanism to operate, and V79 cells with 250 KVp X-rays, which instead make possible the occurrence of both mechanisms. It has been shown that: Maximum sensitization already occurs in bacteria with 10(-2) mol dm-3 ITA (enhancement ratio (ER) 11.2 in oxygen, 2.7 in nitrogen), while in mammalian cells a concentration higher by a factor of 10 is required (ER 2.2 both in air and nitrogen). ITA sensitization is inhibited when bacteria are irradiated in growth medium instead of buffer. Such inhibition does not occur with V79 cells. Cysteine and glycerol completely cancel the sensitizing effect of ITA on bacterial cells in both gas phases. Dimethylsulphoxide (DMSO) does the same in nitrogen, while in oxygen it only reduces ITA sensitization to about 50 per cent of the level observed in control conditions. With mammalian cells, all the three scavengers do not modify significantly the enhancement produced by ITA, either in air or in nitrogen. The experimental results are consistent with both postulated mechanisms of sensitization.

Animals↗
PubMed1987

Radiographic study of intercostal nerve blockade in healthy volunteers.

The spread of solutions injected to the intercostal space was studied in 10 healthy volunteers. Up to 20 ml of a 50:50 mixture of local anaesthetic solution and a radiopaque dye was injected through a modified extradural catheter placed in an intercostal space at the posterior angle of the rib. Radiographic films demonstrated spread by an extrapleural route into adjacent intercostal spaces and this was confirmed by the occurrence of analgesia in the corresponding dermatomes. The relevance of these results to clinical practice is discussed.

Adult↗
PubMed1975

An assessment of the accuracy of computerized transverse axial scanning (EMI scanner) in the diagnosis of intracranial tumour. A review of 366 patients.

The computerized transverse axial (CTA) scans of 366 patients with intracranial tumours and 267 patients without tumours, but with similar presenting features, were analyzed. In all cases the definitive diagnosis was established either by histological or neurological methods. Most tumours were found to be of low tissue density, but a gradation from low through normal to a high density appearance was recognized. Tissue density enhancement with sodium iothalamate was achieved in 63-9% of supratentorial and 62-4% of infratentorial tumours, and usually allowed a more accurate determination to be made of the boundary between the tumour and the surrounding oedema. The accuracy of the CTA scanner as a screening technique was found to be 96%, this being superior to either clinical evaluation or rectilinear isotope scanning. When assessed on the basis of structural abnormalities demonstrated in the same groups of patients, the CTA scans enabled a diagnosis to be made or a lesion excluded in 92-3% of the patients, a figure which bears comparison with arteriography and pneumo-encephalography. It is anticipated that the simplicity and superior sensitivity of the system should decrease the necessity for invasive techniques such as angiography and pneumo-encephalography in the future.

Adenoma↗
PubMed1986

Pharmacokinetics, in-vitro activity, therapeutic efficacy and clinical safety of aztreonam vs. cefotaxime in the treatment of complicated urinary tract infections.

The minimal inhibitory concentrations (MICs) of aztreonam and cefotaxime were determined against 400 isolates from urological in-patients with complicated and/or hospital acquired urinary tract infections (UTI). Against the Gram-negative rods the activities of both antibiotics were comparable except for higher activity of aztreonam against Pseudomonas aeruginosa. The pharmacokinetic study in nine elderly patients showed a prolonged plasma half life of aztreonam (2.7 h) as compared to younger volunteers (1.6-1.9 h). In a prospective randomized study 39 urological patients with complicated and/or hospital acquired UTI were treated with 1 g aztreonam or cefotaxime iv twice daily for 4 to 15 days. Cure was obtained in 5 out of 18 patients in the aztreonam and 7 out of 20 patients in the cefotaxime group. There were 3 superinfections, 7 relapses and 3 reinfections in the aztreonam group and 1 failure, 1 superinfection, 6 relapses and 5 reinfections in the cefotaxime group. There was no significant difference in therapeutic efficacy between the two antibiotics. Both antibiotics were tolerated well and seem to be equally effective in the treatment of complicated UTI caused by sensitive organisms.

Adult↗
PubMed1997

Factors affecting the pharmacokinetics of parenteral chloramphenicol in enteric fever.

Chloramphenicol pharmacokinetics were studied in 29 Nepalese adults diagnosed with uncomplicated enteric fever and randomized to receive succinate ester 30 mg/kg i.v. or i.m. Serial plasma concentrations of chloramphenicol, and iothalamate (to estimate glomerular filtration rate), antipyrine (hepatocellular function) and Indocyanine Green (liver blood flow) were measured by HPLC and kinetic parameters estimated by non-compartmental analysis. In culture-positive patients (n = 16), mean residence times (MRTs) and steady-state volumes of distribution (V(d)ss) for i.v. chloramphenicol (mean +/- S.D.; 4.9 +/- 0.9 h and 1.9 +/- 0.8 L/kg; n = 7) were less than after i.m. chloramphenicol (12.3 +/- 7.3 h and 3.7 +/- 2.5 L/kg; n = 9; P < 0.05), with a higher peak plasma concentration after i.v. (16.2 +/- 9.1 versus 7.8 +/- 3.6 mg/L; P < 0.05); plasma clearance (Cl(p)) was similar in the two groups (368 +/- 172 and 310 +/- 224 mL/kg/min after i.v. and i.m. respectively). In 17 patients examined during convalescence, MRT and Vdss were less than in acute illness regardless of route chloramphenicol administration. There were similar changes in chloramphenicol kinetic parameters in culture-negative patients. Antipyrine Cl(p) and liver blood flow correlated weakly with chloramphenicol Cl(p) in culture-positive patients (P < 0.1) and were higher in convalescence; no such associations were seen for iothalamate Cl(p). These data indicate that i.v. chloramphenicol produces peak plasma concentrations which are on average twice those after i.m. injection of the same dose, due principally to a smaller V(d)ss. Cl(p) is uninfluenced by route of administration and is determined more by hepatic metabolism than renal excretion. Intramuscular treatment may result in sub-therapeutic chloramphenicol concentrations initially, but continued regular i.v. dosing is more likely to produce levels at which bone marrow toxicity occurs.

Adolescent↗
PubMedDate not supplied

HPLC determination of rubber septum contaminants in the iodinated intravenous contrast agent (sodium iothalamate).

A simple and rapid method is described for the determination of 2-mercaptobenzothiazole and mercaptobenzothiazole disulfide leached from rubber closures into the iodinated contrast medium (sodium iothalamate). The contaminants were extracted with methylene chloride and analyzed by high-performance liquid chromatography using ultraviolet detection at wavelengths of 272 and 328 nm. The structures of the impurities were confirmed unequivocally by mass spectrometry. The minimum detectable level was 1 microgram/100 mL (0.01 ppm). The quantitation of contaminants leached from rubber stoppers provides a means for evaluating possible health risks of the extractables.

Benzothiazoles↗
PubMed1998

Optimal design of a two-sample test for assessing [125I]iothalamate plasma clearance in peritoneal dialysis.

BACKGROUND: Plasma clearance of a tracer in peritoneal dialysis (PD) can be used to assess treatment adequacy without labour-intensive fluid collections. Accuracy and precision of plasma clearance estimates by the bolus injection technique depend on the estimation accuracy of the area under the concentration curve and the measurement precision of plasma concentrations. The first source of error is due to oversimplified, e.g. monoexponential, descriptions of plasma disappearance curves. The second source of error arises from the propagation of measurement errors to the parameter estimates. METHODS: The theoretical bias of parameter estimates is determined first for a monoexponential approximation of a biexponential disappearance curve and as a function of the first sampling time at which mixing is still incomplete. The precision of plasma clearance estimates, expressed as coefficient of variation, is then described as a function of the experimental variables and of the standard deviation of measurement error. This allows the determination of the optimal two-sample test that yields most precise estimates of plasma clearance. RESULTS: The optimal two-sample schedules for assessing plasma clearance of [125I]iothalamate in PD patients vary between subjects according to individual clearances and distribution volumes. Our results suggest collecting the first sample 120 min, and the second 2-4 days, after the bolus injection. CONCLUSIONS: The proposed two-sample test is suitable to be used in clinical routine for assessment of adequacy of PD treatment but requires a priori estimation of individual tracer kinetics and of laboratory measurement errors. A fixed design with the first sample taken after 120 min and the second sample collected 3 days after the bolus injection should yield the best performance.

Adult↗
PubMed1999

Rapid and accurate assessment of glomerular filtration rate in patients with renal transplants using serum cystatin C.

BACKGROUND: Assessment of renal function in patients with renal transplants is of great importance. Various studies have reported cystatin C as an easily and rapidly assessable marker that can be used for accurate information on renal function impairment. To date, no study is available to define the role of cystatin C in patients with renal transplants. METHODS: Thirty steady-state patients (50% male/50% female) with status post-kidney transplantation were studied. To assess renal function, cystatin C, creatinine clearance, serum creatinine, beta2-microglobulin (beta2M), and [125I]iothalamate clearance were determined. Correlations and non-parametric ROC curves for accuracy, using a cut-off glomerular filtration rate (GFR) of 60 ml/min, were obtained for the different markers allowing for calculations of positive predictive values (PPV), positive likelihood ratios (PLR), specificity and sensitivity, respectively. Further, to evaluate the usefulness of these markers for monitoring, intraindividual coefficients of variation (CVs) for cystatin C and creatinine measurements were compared in 85 renal transplant patients. Measurements consisted of at least six pairs of results, which were obtained at different time points during routine follow-up. RESULTS: Cystatin C correlated best with GFR (r=0.83), whereas serum creatinine (r=0.67), creatinine clearance (r=0.57) and beta2M (r=0.58) all had lower correlation coefficients. The diagnostic accuracy of cystatin C was significantly better than serum creatinine (P=0.025), but did not differ significantly from creatinine clearance (P=0.76) and beta2M (P=0.43). At a cut-off of 1.64 mg/l, cystatin C has a PPV of 93%, PLR of 6.4, specificity 89% and sensitivity 70%, respectively. For beta2M, PPV 83%, PLR 1.7, specificity 67% and sensitivity 75% was seen at a cut-off of 3.57 mg/l. Accordingly, at a cut-off of 125 micromol/l for serum creatinine, a PPV 76%, PLR 1.4, specificity 44% and sensitivity 80% was revealed. Finally, at a cut-off of 66 ml/min/1.73 m2 for creatinine clearance, the following characteristics were found: PPV 94%, PLR 7.7, specificity 89% and sensitivity 85%. The intraindividual variation of creatinine was significantly lower than that of cystatin C (P<0.001). With increasing concentrations, their ratios of CV tended towards a value of 1, demonstrating identical variability at low GFR. CONCLUSION: Together, our data show that in patients with renal transplants, cystatin C, in terms of PPV and PLR, has a similar diagnostic value as creatinine clearance. However, it is superior to serum determinations of creatinine and beta2M. The intraindividual variation of cystatin C is greater than that of creatinine. This might be due to the better ability of cystatin C to reflect temporary changes especially in mildly impaired GFR, most critical for early detection of rejection and other function impairment. Thus, cystatin C allows for rapid and accurate assessment of renal function (GFR) in renal transplants and is clearly superior to the commonly used serum creatinine.

Adult↗
PubMed2006

Renal extraction of cystatin C vs 125I-iothalamate in hypertensive patients.

BACKGROUND: Several markers are available to estimate the glomerular filtration rate (GFR) in patients. Cystatin C is a relatively new marker and has been suggested as an alternative for creatinine. Numerous studies have been performed to evaluate the usefulness of cystatin C to estimate GFR. The aim of this study is to compare the renal extraction of cystatin C with that of 125I-iothalamate in hypertensive patients. METHODS: Forty hypertensive patients with unilateral renal artery stenosis, and who used at least two antihypertensive agents, were studied. For the determination of the renal extraction ratio, blood samples were drawn simultaneously from the renal vein and the abdominal aorta. The renal extraction ratio was calculated as ([A]-[V])/[A], in which A is the plasma concentration of the compound from the abdominal aorta, and V is the plasma concentration of the compound from the renal vein. RESULTS: The mean difference between the renal extraction ratio of cystatin C and that of 125I-iothalamate was 0.002. The 95% confidence interval (CI) for the mean difference was -0.036 to 0.032, which was not statistically significant. However, the limits of agreement were large (-0.271 and 0.267). CONCLUSIONS: Despite a lower reported glomerular sieving coefficient of cystatin C, the mean renal extraction of cystatin C was equal to the mean renal extraction of 125I-iothalamate in hypertensive patients, suggesting tubular secretion of cystatin C. Combined with the large variation in the renal extraction of cystatin C, these findings cast doubts on its usefulness as a glomerular filtration marker.

Adult↗
PubMed2006

Are prediction equations for glomerular filtration rate useful for the long-term monitoring of type 2 diabetic patients?

BACKGROUND: The aim of this study was to compare the accuracy of prediction equations [modification of diet in renal disease (MDRD), simplified MDRD, Cockcroft-Gault (CG), reciprocal of creatinine and creatinine clearance] in a cohort of patients with type 2 diabetes. METHODS: A total of 525 glomerular filtration rates (GFRs) using (125)I-iothalamate were carried out over 10 years in 87 type 2 diabetic patients. Accuracy was evaluated at three levels of renal function according to the baseline values obtained with the isotopic method: hyperfiltration (GFR: >140 ml/min/1.73 m(2); 140 isotopic determinations in 27 patients), normal renal function (GFR: 140-90 ml/min/1.73 m(2); 294 isotopic determinations in 47 patients) and chronic kidney disease (CKD) stages 2-3 (GFR: 30-89 ml/min/1.73 m(2); 87 isotopic determinations in 13 patients). The annual slope for GFR (change in GFR expressed as ml/min/year) was considered to ascertain the variability in the equations compared with the isotopic method during follow-up. Student's t-test was used to determine the existence of significant differences between prediction equations and the isotopic method (P < 0.05 with Bonferroni adjusted for five contrast tests). RESULTS: In the subgroup of patients with hyperfiltration, a GFR slope calculated with (125)I-iothalamate -4.8 +/- 4.7 ml/min/year was obtained. GFR slope in patients with normal renal function was -3.0 +/- 2.3 ml/min/year. In both situations, all equations presented a significant underestimation compared with the isotopic GFR (P < 0.01; P < 0.05). In the subgroup of CKD stages 2-3, the slope for GFR with (125)I-iothalamate was -1.4 +/- 1.8 ml/min/year. The best prediction equation compared with the isotopic method proved to be MDRD with a slope for GFR of -1.4 +/- 1.3 ml/min/year (P: NS) compared with the CG formula -1.0 +/- 0.9 ml/min/year (P: NS). Creatinine clearance presented the greatest variability in estimation (P < 0.001). CONCLUSIONS: In the normal renal function and hyperfiltration groups, none of the prediction equations demonstrated acceptable accuracy owing to excessive underestimation of renal function. In CKD stages 2-3, with mean serum creatinine > or =133 micromol/l (1.5 mg/dl), the MDRD equation can be used to estimate GFR during the monitoring and follow-up of patients with type 2 diabetes receiving insulin, anti-diabetic drugs or both.

Adult↗
PubMed1983

Iopamidol: a new contrast medium in coronary angiography. Comparison, on electrophysiological changes in man, with a commonly used contrast medium.

In 30 patients undergoing coronary angiography the effects of Iopamidol on sinus node activity, atrioventricular and intraventricular conduction were evaluated using His Bundle recordings, and compared to the effects produced by Diatrizoate. Diatrizoate resulted in an increase in sinus cycle length and prolonged AV nodal conduction, resulting in second degree AV block in two patients. Iopamidol had significantly less effect on sinus cycle (P less than 0.01) and AV nodal conduction (P less than 0.01). Neither contrast media affected intraventricular conduction. No difference was noted in the imaging power of the two contrast media. It is suggested that non-ionic, low osmotic contrast media such as Iopamidol will result in increased patient safety during coronary angiography without loss of imaging power.

Adult↗
PubMed1984

Effects of contrast media used in angiocardiography on the mechanical performance and the relaxation of normal and ischaemic myocardium.

The aim of this study was to investigate the mechanisms of the cardiodepressive action of ionic and non-ionic contrast media currently used in coronary arteriography. Experiments carried out on isolated preparations of cat papillary muscle, treated with increasing concentrations of Telebrix 39, Radioselectan, Hexabrix and Iopamidol 370 and 300, on the one hand and, on the other hand, a pre-determined dose of Telebrix and Iopamidol 300 during hypoxia and subsequent reoxygenation, showed that, at constant Ca2+ concentrations: (1) The cardiodepressive effects of contrast media are correlated with the hyperosmolality that they induce. When osmolality was higher than 400 mOsm, all the products caused a reduction of the peak force (PF: 40.49 +/- 5.15%), the maximum velocity of contraction (Vmax: 39.85 +/- 3.66%) and of the peak velocity of relaxation (Vrelax: 23.30 +/- 2.20%) (P less than 0.01). The time to peak force (TPF), on the other hand, remained constant, whereas the half-relaxation time (THR) was increased. No significant differences were observed between these effects and those induced by control iso-osmolar solutions when the same osmolality was induced. In practice, however, the critical hyperosmolality value of 400 mOsm is never reached when using non-ionic contrast media such as Hexabrix and Iopamidol 300. This could explain the excellent tolerance to these substances. (2) During hypoxia and reoxygenation, the effect of hyperosmolality is more marked. Thus, the non-ionic contrast medium, Iopamidol 300 (340 mOsm), reduces the hypoxic contractility depression (PF: 53.10 +/- 2.60% compared to the control values of 47.60 +/- 5.00%, P less than 0.01), whereas, at the same dose, the ionic medium Telebrix is hyperosmolar (440 mOsm) and induces a more pronounced hypoxic depression of contractility (P less than 0.01). The critical hyperosmolality is never reached during ventriculography (320 mOsm), whatever the medium used, but it can be observed during coronary arteriography. It is, therefore, important to use non-ionic contrast media in the investigation of unstable angina and of acute myocardium infarction.

Angiocardiography↗
PubMed2005

Sensitivity variation of doped Fricke gel irradiated with monochromatic synchrotron X rays between 33.5 and 80 keV.

An experimental binary radiotherapy proposes the concomitant use of a high-Z compound and synchrotron X rays for enhancing radiation dose selectively in tumours by a photoelectric effect. This study aimed at measuring the resulting dose enhancement in irradiated material. A doped Fricke gel dosemeter model was manufactured with 10 mg ml(-1) of iodine (Telebrix) or barium (Micropaque). Samples were irradiated with a monochromatic synchrotron beam at 33.5, 50, 65 and 80 keV. The ensuing enhancement of the sensitivity of the dosemeter was derived from the nuclear magnetic resonance relaxation rates measured at different X-ray doses. Our results demonstrate (1) the preservation of a linear relationship between relaxation rates and X-ray doses for dosemeters doped with high-Z atoms and (2) a clear energy-dependent sensitivity enhancement for barium-doped Fricke gels. This enhancement was neither reproducible with iodinated compounds nor clearly related to the expected dose enhancement factor. However 1% barium sulphate in the gel could significantly improve the gel's response when it was irradiated by low-energy X rays.

Barium Sulfate↗